THE ARGUMENT FROM PALEONTOLOGY 71 



demand an explanation of these facts, and that 

 this explanation is in our power to find. It is 

 to Wallace that we are especially indebted for 

 our knowledge of the geographical distribution of 

 animals. 



The nature of the problems we have to consider 

 is best shown by examples, of which the following 

 will serve our purpose. 



A. Camelid.£, or Camels, are an exceedingly 

 restricted group, the majority of species now living 

 in domestication. 



1. Camelus is highly characteristic of hot, parched 

 deserts, and is found in Sahara, Arabia, Persia, 

 Turkestan, and Mongolia, as far as Lake Baikal. 

 There are none now living perfectly wild. Of 

 Camelus there are two kinds : the dromedary, found 

 in Asia Minor and Africa, has one hump ; the 

 Bactrian camel, possessing two humps, is confined to 

 Asia, and especially Central Asia, north of the 

 Himalayas. 



2. Auchenia is of smaller size, with slender legs, 

 and has no hump. It is confined to the mountainous 

 and desert regions of the southern part of South 

 America, and is often found on rugged snow-clad 

 slopes at great elevations. Of this group, Llama 

 and Alpaca are entirely domesticated — the former 

 being used as a beast of burden in Peru and Bolivia ; 

 the latter is cultivated both for its wool and for its 

 flesh. Vicuna, the smallest member of the group, 

 is found at elevations of 13,000 feet and upwards, 

 in the Andes of Peru, Ecuador, and Bolivia. 

 Guanaco, an animal the size of a fallow-deer, is 



